The human vertebrae and associated connective elements are subject to a variety of diseases and conditions which cause pain and disability. Among these diseases and conditions are spondylosis, spondylolisthesis, vertebral instability, spinal stenosis and degenerated, herniated, or degenerated and herniated intervertebral discs. Additionally, the vertebrae and associated connective elements are subject to injuries, including fractures and torn ligaments and surgical manipulations, including laminectomies.
The pain and disability related to these diseases, conditions, injuries and manipulations often results from the displacement of all or part of a vertebra from the remainder of the vertebral column. A variety of methods have been developed to restore the displaced vertebrae or portions of displaced vertebrae to their normal position and to fix them within the vertebral column. For example, open reduction with screw fixation is one currently used method. These methods, however, are associated with a variety of disadvantages, such as high cost, lengthy inpatient hospital stays and the potential morbidity associated with open procedures.
Therefore, there is a need for a method of repositioning and fixing displaced vertebrae or portions of displaced vertebrae to a position within the vertebral column which is more stable or which causes less morbidity. Further, there is a need for a system for performing a method of repositioning and fixing displaced vertebrae or portions of displaced vertebrae to a position within the vertebral column which is more stable or which causes less morbidity.
According to one embodiment of the present invention, there is provided a bone screw comprising a proximal portion comprising a head with a proximal end and a portal; a distal portion comprising threads and a tip with a distal end; and a central lumen configured to receive a guidewire extending coaxially completely through the bone screw from the proximal end to the distal end. The head comprises a proximal portion configured to mate with the tip of a screwdriver.
According to another embodiment of the present invention, there is provided a screwdriver comprising a proximal end comprising a handle configured to permit grasping of the screwdriver and to permit the application of torque to a bone screw; a distal end comprising a shaft having a tip configured to interface with a bone screw; and a central lumen configured to receive a guidewire extending coaxially completely through the screwdriver from the proximal end to the distal end.
According to yet another embodiment of the present invention, there is provided an inflatable connection rod comprising a proximal end comprising a self-sealing valve; a distal end comprising a tip; and a compliant, inflatable balloon between the proximal end and the distal end. The balloon comprises thin, reinforcing wires.
According to another embodiment of the present invention, there is provided a directing sheath comprising a proximal portion with a proximal end; a distal portion with a distal end; a central portion between the proximal portion and the distal portion comprising at least two openings; and a lumen extending through the directing sheath from the proximal end to distal end. The directing sheath is preferably scored along its longitudinal axis to allow the directing sheath to be split into two separate halves by peeling the directing sheath apart at either its proximal end or its distal end or both along the scoring.
In a preferred embodiment of the present invention, there is provided a method of repositioning or fixing one or more unstable, separated or displaced vertebrae or one or more portions of one or more vertebrae in a patient""s vertebral column. The method comprises:
a) identifying a patient who is a suitable candidate for undergoing the method;
b) making a stab incision in the patient""s skin overlying the patient""s vertebral column at or near the level of the vertebrae or portion of vertebrae to be repositioned or fixed;
c) creating a first tract from the incision to the posterior periosteal surface of the vertebrae;
d) incising the periosteum and extending the first tract into the cortex of the vertebrae;
e) inserting a first guidewire into the first tract;
f) advancing a bone screw comprising a portal and a tip, and a screwdriver over the first guidewire;
g) applying torque to the bone screw using the screwdriver, thereby fixing part of the tip of the bone screw into the vertebrae while the portal of the bone screw is exterior and dorsal to the vertebrae and the portal is open parallel to the long axis of the vertebral column;
h) removing the screwdriver and the first guidewire;
i) repeating c) through h) for at least one vertebrae which is neither unstable, separated or displaced and which is adjacent the vertebrae or portion of the vertebrae that is being repositioned or fixed, or repeating c) through h) for the cranial-ward portion of the sacrum of the patient;
j) inserting an inflatable connection rod comprising a proximal end, a distal end and an inflatable balloon between the proximal end and the distal end, between the portals of the bone screws; and
k) inflating the inflatable balloon thereby creating a rigid structure between the inflated inflatable connection rod and the bone screws;
thereby repositioning or fixing the one or more unstable, separated or displaced vertebrae or the one or more portions of one or more vertebrae unilaterally.
Identifying a patient who is a suitable candidate comprises identifying a patient who has one or more unstable vertebrae, one or more portions of a vertebrae at least partly separated from the remainder of the vertebrae with potential or complete separation, or who has one or more vertebrae or a portion of one or more vertebrae displaced from its normal position relative to the vertebral column, or who has one or more portions of a vertebrae at least partly separated from the remainder of the vertebrae and displaced from its normal position relative to the vertebral column; and where the patient has either pain, loss of function or real or potential instability which is likely due to the separation or displacement, or separation and displacement.
The method can comprise enlarging the first tract from the incision to the posterior periosteal surface using a high-pressure fascial dilator balloon after creating the first tract. Further, inserting an inflatable connection rod can comprise:
i) percutaneously inserting a hollow needle and advancing the hollow needle to the portal of one of the bone screws;
ii) introducing a second guidewire through the lumen of the hollow needle and into the portal of one of the bone screws; and
iii) passing the second guidewire through all of the portals in the bone screws, thereby creating a second tract.
The method can also comprise:
i) dilating the second tract created by the second guidewire using a high pressure balloon;
ii) passing an introducer sheath over the guidewire along the entire guidewire second tract;
iii) removing the guidewire; and
iv) advancing the inflatable connection rod through the introducer sheath until the inflatable connection rod advances between the bone screw portals.
The method can also comprise using a guidewire directing device to direct the advancing second guidewire through at least one bone screw portal, or can comprise using a guidewire capture device to pull the second guidewire through the patient""s skin. Further, inflating the inflatable balloon can comprise inflating the balloon with a rapid setting, liquid polymer.
In a particularly preferred embodiment, the method further comprises repeating c) through h) for one additional vertebrae, where the one additional vertebrae is either unstable, separated or displaced, or where one or more portions of the one additional vertebrae is unstable, separated or displaced. In another particularly preferred embodiment, the method further comprises repeating b) through k) on the opposite side of the spinous processes of the patient""s vertebrae column, thereby repositioning or fixing the one or more unstable, separated or displaced vertebrae or the one or more portions of one or more vertebrae bilaterally.
In a preferred embodiment, the method further comprises using a directing sheath to position the bone screws.
According to another embodiment of the present invention, there is provided a method of repositioning or fixing a first vertebrae that is unstable, separated or displaced or that has one or more unstable, separated or displaced portions. The method comprises:
a) fixing one or more than one bone screw in the first vertebrae and one or more than one bone screw in a second vertebrae;
b) inserting an inflatable balloon between the portal of the bone screw in the first vertebrae and the portal of the bone screw in the second vertebrae; and
c) inflating the inflatable balloon thereby creating a rigid structure between the balloon and the bone screws;
thereby repositioning or fixing the first vertebrae or portion of the first vertebrae.
In a preferred embodiment, the method further comprises advancing each bone screw over a guidewire before a). In another preferred embodiment, a) comprises applying torque to each bone screw using a screwdriver advanced over a guidewire. In another preferred embodiment, c) comprises inflating the balloon with a rapid setting, liquid polymer.
In a particularly preferred embodiment, the method further comprises repeating a) through c) on the opposite side of the spinous processes of the patient""s vertebrae column, thereby bilaterally repositioning or fixing the one or more unstable, separated or displaced vertebrae or the one or more portions of one or more vertebrae. In a preferred embodiment, the method further comprises using a directing sheath to position the bone screws before a).
According to.another embodiment of the present invention, there is provided a kit for repositioning or fixing a first vertebrae that is unstable, separated or displaced or that has one or more unstable, separated or displaced portions. The kit comprises one or more devices selected from the group consisting of a bone screw according to the present invention, a screwdriver according to the present invention, an inflatable connection rod according to the present invention, and a directing sheath according to the present invention.